1. Photosynthesis: Using Light to Make Food
Chapter 7
Photosynthesis: Using Light to Make Food

2. Biology and Society: Biofuels
Wood has historically been the main fuel used to produce
heat and
light.
© 2013 Pearson Education, Inc. 2

3. Figure 7.0
Figure 7.0 Capturing solar energy 3

4. Biology and Society: Biofuels
Industrialized societies replaced wood with fossil fuels including
coal,
gas, and
oil.
To limit the damaging effects of fossil fuels, researchers are investigating the use of biomass (living material) as efficient and renewable energy sources.
© 2013 Pearson Education, Inc. 4

5. Biology and Society: Biofuels
There are several types of biofuels.
Bioethanol is a type of alcohol produced by the fermentation of glucose made from starches in crops such as grains, sugar beets, and sugar cane.
Bioethanol may be used
directly as a fuel source in specially designed vehicles or
as a gasoline additive.
© 2013 Pearson Education, Inc. 5

6. Biology and Society: Biofuels
Cellulosic ethanol is a type of bioethanol made from cellulose in nonedible plant material such as wood or grass.
Biodiesel is made from plant oils or recycled frying oil.
© 2013 Pearson Education, Inc. 6

7. THE BASICS OF PHOTOSYNTHESIS
is used by plants, algae (protists), and some bacteria,
transforms light energy into chemical energy, and
uses carbon dioxide and water as starting materials.
© 2013 Pearson Education, Inc.
Student Misconceptions and Concerns
1. Students often do not fully understand how the burning of fossil fuels contributes to global warming. They might wonder, “How does the burning of fossil fuels differ from the burning of ethanol produced from crops?” Students might not realize that the carbon in fossil fuels was removed from the atmosphere hundreds of millions of years ago, while the carbon in crops was removed much more recently, when the crops were grown. The use of ethanol as an alternative is complicated by the typical reliance upon fossil fuels for ethanol production.
2. Some students do not realize that plant cells also have mitochondria. Instead, they assume that the chloroplasts are sufficient for the plant cell’s needs. But nearly 50% of the carbohydrates produced by plant cells are used for cellular respiration (involving mitochondria).
3. Students may not connect the growth in plant mass to the fixation of carbon during the Calvin cycle. It can be difficult for many students to appreciate that molecules in air can contribute significantly to the mass of plants.
4. Students may understand the overall chemical relationships between photosynthesis and cellular respiration, but many struggle to understand the use of carbon dioxide in the Calvin cycle. Photosynthesis is much more than gas exchange.
5. Students who have not read all of Chapter 7 may not realize that glucose is not the direct product of photosynthesis. Although glucose is shown as a product of photosynthesis, a three-carbon sugar is directly produced (G3P). A plant can use G3P to make many types of organic molecules, including glucose. (The authors address the production of G3P under the section “The Calvin Cycle” later in this chapter.)
Teaching Tips
1. When introducing the diverse ways that plants impact our lives, consider challenging your students to come up with a list of products made from plants that they encounter regularly. Perhaps you might only list those encountered in a single day of college life. The list can be surprising and help to build up your “catalog of examples.”
2. The living world contains many examples of adaptations to increase surface area. Some examples are the many folds of the inner mitochondrial membrane, the highly branched surfaces of fish gills and human lungs, and the highly branched system of capillaries in the tissues of our bodies. Consider relating this broad principle seen elsewhere to the extensive folding of the thylakoid membranes.
3. In our world, energy is frequently converted to a usable form in one place and used in another. For example, electricity is generated by power plants, transferred to our homes, and used to run computers, create light, and help us prepare foods. Consider relating this common energy transfer to the two-stage process of photosynthesis.
4. You might wish to discuss the evolution of chloroplasts from photosynthetic prokaryotes if you will not address this subject elsewhere in your course.
5. Figure 7.3 is an important visual organizer that notes the key structures and functions of the two stages of photosynthesis. This figure reminds students where water and sunlight are used in the thylakoid membranes to generate oxygen, ATP, and NADPH. The second step, in the stroma, reveals the use of carbon dioxide, ATP, and NADPH to generate carbohydrates.
6. The thylakoid space and the intermembrane space of a mitochondrion have analogous roles. Students might be encouraged to create a list of the similarities in structure and function of mitochondria and chloroplasts through these related chapters. 7

8. THE BASICS OF PHOTOSYNTHESIS
The chemical energy produced via photosynthesis is stored in the bonds of sugar molecules.
Organisms that use photosynthesis are
photosynthetic autotrophs and
the producers for most ecosystems.
© 2013 Pearson Education, Inc.
Student Misconceptions and Concerns
1. Students often do not fully understand how the burning of fossil fuels contributes to global warming. They might wonder, “How does the burning of fossil fuels differ from the burning of ethanol produced from crops?” Students might not realize that the carbon in fossil fuels was removed from the atmosphere hundreds of millions of years ago, while the carbon in crops was removed much more recently, when the crops were grown. The use of ethanol as an alternative is complicated by the typical reliance upon fossil fuels for ethanol production.
2. Some students do not realize that plant cells also have mitochondria. Instead, they assume that the chloroplasts are sufficient for the plant cell’s needs. But nearly 50% of the carbohydrates produced by plant cells are used for cellular respiration (involving mitochondria).
3. Students may not connect the growth in plant mass to the fixation of carbon during the Calvin cycle. It can be difficult for many students to appreciate that molecules in air can contribute significantly to the mass of plants.
4. Students may understand the overall chemical relationships between photosynthesis and cellular respiration, but many struggle to understand the use of carbon dioxide in the Calvin cycle. Photosynthesis is much more than gas exchange.
5. Students who have not read all of Chapter 7 may not realize that glucose is not the direct product of photosynthesis. Although glucose is shown as a product of photosynthesis, a three-carbon sugar is directly produced (G3P). A plant can use G3P to make many types of organic molecules, including glucose. (The authors address the production of G3P under the section “The Calvin Cycle” later in this chapter.)
Teaching Tips
1. When introducing the diverse ways that plants impact our lives, consider challenging your students to come up with a list of products made from plants that they encounter regularly. Perhaps you might only list those encountered in a single day of college life. The list can be surprising and help to build up your “catalog of examples.”
2. The living world contains many examples of adaptations to increase surface area. Some examples are the many folds of the inner mitochondrial membrane, the highly branched surfaces of fish gills and human lungs, and the highly branched system of capillaries in the tissues of our bodies. Consider relating this broad principle seen elsewhere to the extensive folding of the thylakoid membranes.
3. In our world, energy is frequently converted to a usable form in one place and used in another. For example, electricity is generated by power plants, transferred to our homes, and used to run computers, create light, and help us prepare foods. Consider relating this common energy transfer to the two-stage process of photosynthesis.
4. You might wish to discuss the evolution of chloroplasts from photosynthetic prokaryotes if you will not address this subject elsewhere in your course.
5. Figure 7.3 is an important visual organizer that notes the key structures and functions of the two stages of photosynthesis. This figure reminds students where water and sunlight are used in the thylakoid membranes to generate oxygen, ATP, and NADPH. The second step, in the stroma, reveals the use of carbon dioxide, ATP, and NADPH to generate carbohydrates.
6. The thylakoid space and the intermembrane space of a mitochondrion have analogous roles. Students might be encouraged to create a list of the similarities in structure and function of mitochondria and chloroplasts through these related chapters.

9. Photosynthetic Protists Photosynthetic Bacteria
Figure 7.1
PHOTOSYNTHETIC AUTOTROPHS
Plants
(mostly on land)
Photosynthetic Protists
(aquatic)
Photosynthetic Bacteria
(aquatic) LM
Forest plants
Kelp, a large, multicellular alga
Micrograph of cyanobacteria
Figure 7.1 A diversity of photosynthetic autotrophs 9

10. Plants (mostly on land)
Figure 7.1a
Plants
(mostly on land)
Forest plants
Figure 7.1 A diversity of photosynthetic autotrophs (part 1) 10

11. Photosynthetic Protists
Figure 7.1b
Photosynthetic Protists
(aquatic)
Kelp, a large, multicellular alga
Figure 7.1 A diversity of photosynthetic autotrophs (part 2) 11

12. Photosynthetic Bacteria
Figure 7.1c
Photosynthetic Bacteria
(aquatic) LM
Micrograph of cyanobacteria
Figure 7.1 A diversity of photosynthetic autotrophs (part 3) 12

13. Chloroplasts: Sites of Photosynthesis
Chloroplasts are
the site of photosynthesis and
found mostly in the interior cells of leaves.
Inside chloroplasts are interconnected, membranous sacs called thylakoids, which are suspended in a thick fluid called stroma.
Thylakoids are concentrated in stacks called grana.
© 2013 Pearson Education, Inc.
Student Misconceptions and Concerns
1. Students often do not fully understand how the burning of fossil fuels contributes to global warming. They might wonder, “How does the burning of fossil fuels differ from the burning of ethanol produced from crops?” Students might not realize that the carbon in fossil fuels was removed from the atmosphere hundreds of millions of years ago, while the carbon in crops was removed much more recently, when the crops were grown. The use of ethanol as an alternative is complicated by the typical reliance upon fossil fuels for ethanol production.
2. Some students do not realize that plant cells also have mitochondria. Instead, they assume that the chloroplasts are sufficient for the plant cell’s needs. But nearly 50% of the carbohydrates produced by plant cells are used for cellular respiration (involving mitochondria).
3. Students may not connect the growth in plant mass to the fixation of carbon during the Calvin cycle. It can be difficult for many students to appreciate that molecules in air can contribute significantly to the mass of plants.
4. Students may understand the overall chemical relationships between photosynthesis and cellular respiration, but many struggle to understand the use of carbon dioxide in the Calvin cycle. Photosynthesis is much more than gas exchange.
5. Students who have not read all of Chapter 7 may not realize that glucose is not the direct product of photosynthesis. Although glucose is shown as a product of photosynthesis, a three-carbon sugar is directly produced (G3P). A plant can use G3P to make many types of organic molecules, including glucose. (The authors address the production of G3P under the section “The Calvin Cycle” later in this chapter.)
Teaching Tips
1. When introducing the diverse ways that plants impact our lives, consider challenging your students to come up with a list of products made from plants that they encounter regularly. Perhaps you might only list those encountered in a single day of college life. The list can be surprising and help to build up your “catalog of examples.”
2. The living world contains many examples of adaptations to increase surface area. Some examples are the many folds of the inner mitochondrial membrane, the highly branched surfaces of fish gills and human lungs, and the highly branched system of capillaries in the tissues of our bodies. Consider relating this broad principle seen elsewhere to the extensive folding of the thylakoid membranes.
3. In our world, energy is frequently converted to a usable form in one place and used in another. For example, electricity is generated by power plants, transferred to our homes, and used to run computers, create light, and help us prepare foods. Consider relating this common energy transfer to the two-stage process of photosynthesis.
4. You might wish to discuss the evolution of chloroplasts from photosynthetic prokaryotes if you will not address this subject elsewhere in your course.
5. Figure 7.3 is an important visual organizer that notes the key structures and functions of the two stages of photosynthesis. This figure reminds students where water and sunlight are used in the thylakoid membranes to generate oxygen, ATP, and NADPH. The second step, in the stroma, reveals the use of carbon dioxide, ATP, and NADPH to generate carbohydrates.
6. The thylakoid space and the intermembrane space of a mitochondrion have analogous roles. Students might be encouraged to create a list of the similarities in structure and function of mitochondria and chloroplasts through these related chapters. 13

14. Chloroplasts: Sites of Photosynthesis
The green color of chloroplasts is from chlorophyll, a light-absorbing pigment that plays a central role in converting solar energy to chemical energy.
Stomata are tiny pores in leaves where
carbon dioxide enters and
oxygen exits.
© 2013 Pearson Education, Inc.
Student Misconceptions and Concerns
1. Students often do not fully understand how the burning of fossil fuels contributes to global warming. They might wonder, “How does the burning of fossil fuels differ from the burning of ethanol produced from crops?” Students might not realize that the carbon in fossil fuels was removed from the atmosphere hundreds of millions of years ago, while the carbon in crops was removed much more recently, when the crops were grown. The use of ethanol as an alternative is complicated by the typical reliance upon fossil fuels for ethanol production.
2. Some students do not realize that plant cells also have mitochondria. Instead, they assume that the chloroplasts are sufficient for the plant cell’s needs. But nearly 50% of the carbohydrates produced by plant cells are used for cellular respiration (involving mitochondria).
3. Students may not connect the growth in plant mass to the fixation of carbon during the Calvin cycle. It can be difficult for many students to appreciate that molecules in air can contribute significantly to the mass of plants.
4. Students may understand the overall chemical relationships between photosynthesis and cellular respiration, but many struggle to understand the use of carbon dioxide in the Calvin cycle. Photosynthesis is much more than gas exchange.
5. Students who have not read all of Chapter 7 may not realize that glucose is not the direct product of photosynthesis. Although glucose is shown as a product of photosynthesis, a three-carbon sugar is directly produced (G3P). A plant can use G3P to make many types of organic molecules, including glucose. (The authors address the production of G3P under the section “The Calvin Cycle” later in this chapter.)
Teaching Tips
1. When introducing the diverse ways that plants impact our lives, consider challenging your students to come up with a list of products made from plants that they encounter regularly. Perhaps you might only list those encountered in a single day of college life. The list can be surprising and help to build up your “catalog of examples.”
2. The living world contains many examples of adaptations to increase surface area. Some examples are the many folds of the inner mitochondrial membrane, the highly branched surfaces of fish gills and human lungs, and the highly branched system of capillaries in the tissues of our bodies. Consider relating this broad principle seen elsewhere to the extensive folding of the thylakoid membranes.
3. In our world, energy is frequently converted to a usable form in one place and used in another. For example, electricity is generated by power plants, transferred to our homes, and used to run computers, create light, and help us prepare foods. Consider relating this common energy transfer to the two-stage process of photosynthesis.
4. You might wish to discuss the evolution of chloroplasts from photosynthetic prokaryotes if you will not address this subject elsewhere in your course.
5. Figure 7.3 is an important visual organizer that notes the key structures and functions of the two stages of photosynthesis. This figure reminds students where water and sunlight are used in the thylakoid membranes to generate oxygen, ATP, and NADPH. The second step, in the stroma, reveals the use of carbon dioxide, ATP, and NADPH to generate carbohydrates.
6. The thylakoid space and the intermembrane space of a mitochondrion have analogous roles. Students might be encouraged to create a list of the similarities in structure and function of mitochondria and chloroplasts through these related chapters. 14

15. 15 Photosynthetic cells Vein Stomata Leaf cross section Figure 7.2-1
CO2 O2
Stomata
Leaf cross section
Figure 7.2 Journey into a leaf (step 1) 15

16. 16 Chloroplast Photosynthetic cells Vein Stomata Leaf cross section
Figure 7.2-2
Photosynthetic
cells
Chloroplast
Vein
CO2 O2
Stomata LM
Leaf cross section
Interior cell
Figure 7.2 Journey into a leaf (step 2) 16

17. 17 Chloroplast Photosynthetic cells Inner and outer membranes Vein
Figure 7.2-3
Photosynthetic
cells
Chloroplast
Inner and outer
membranes
Vein
Thylakoid
space
Stroma
Granum
CO2 O2
Stomata LM
Leaf cross section
Interior cell
Colorized TEM
Figure 7.2 Journey into a leaf (step 3) 17

18. 18 Vein (transports water and nutrients) Photosynthetic cells Stomata
Figure 7.2a
Vein
(transports
water and
nutrients)
Photosynthetic
cells
CO2 O2
Stomata
Leaf cross section
Figure 7.2 Journey into a leaf (part 1) 18

19. 19 Chloroplast Inner and outer membranes Thylakoid Stroma space Granum
Figure 7.2b
Chloroplast
Inner and outer
membranes
Thylakoid
space
Stroma
Granum LM
Interior cell
Colorized TEM
Figure 7.2 Journey into a leaf (part 2) 19

20. 20 Chloroplast Interior cell LM Figure 7.2c
Figure 7.2 Journey into a leaf (part 3) 20

21. 21 Stroma Granum Colorized TEM Figure 7.2d
Figure 7.2 Journey into a leaf (part 4) 21

22. The Simplified Equation for Photosynthesis
In the overall equation for photosynthesis, notice that the reactants of photosynthesis are the waste products of cellular respiration.
© 2013 Pearson Education, Inc.
Student Misconceptions and Concerns
1. Students often do not fully understand how the burning of fossil fuels contributes to global warming. They might wonder, “How does the burning of fossil fuels differ from the burning of ethanol produced from crops?” Students might not realize that the carbon in fossil fuels was removed from the atmosphere hundreds of millions of years ago, while the carbon in crops was removed much more recently, when the crops were grown. The use of ethanol as an alternative is complicated by the typical reliance upon fossil fuels for ethanol production.
2. Some students do not realize that plant cells also have mitochondria. Instead, they assume that the chloroplasts are sufficient for the plant cell’s needs. But nearly 50% of the carbohydrates produced by plant cells are used for cellular respiration (involving mitochondria).
3. Students may not connect the growth in plant mass to the fixation of carbon during the Calvin cycle. It can be difficult for many students to appreciate that molecules in air can contribute significantly to the mass of plants.
4. Students may understand the overall chemical relationships between photosynthesis and cellular respiration, but many struggle to understand the use of carbon dioxide in the Calvin cycle. Photosynthesis is much more than gas exchange.
5. Students who have not read all of Chapter 7 may not realize that glucose is not the direct product of photosynthesis. Although glucose is shown as a product of photosynthesis, a three-carbon sugar is directly produced (G3P). A plant can use G3P to make many types of organic molecules, including glucose. (The authors address the production of G3P under the section “The Calvin Cycle” later in this chapter.)
Teaching Tips
1. When introducing the diverse ways that plants impact our lives, consider challenging your students to come up with a list of products made from plants that they encounter regularly. Perhaps you might only list those encountered in a single day of college life. The list can be surprising and help to build up your “catalog of examples.”
2. The living world contains many examples of adaptations to increase surface area. Some examples are the many folds of the inner mitochondrial membrane, the highly branched surfaces of fish gills and human lungs, and the highly branched system of capillaries in the tissues of our bodies. Consider relating this broad principle seen elsewhere to the extensive folding of the thylakoid membranes.
3. In our world, energy is frequently converted to a usable form in one place and used in another. For example, electricity is generated by power plants, transferred to our homes, and used to run computers, create light, and help us prepare foods. Consider relating this common energy transfer to the two-stage process of photosynthesis.
4. You might wish to discuss the evolution of chloroplasts from photosynthetic prokaryotes if you will not address this subject elsewhere in your course.
5. Figure 7.3 is an important visual organizer that notes the key structures and functions of the two stages of photosynthesis. This figure reminds students where water and sunlight are used in the thylakoid membranes to generate oxygen, ATP, and NADPH. The second step, in the stroma, reveals the use of carbon dioxide, ATP, and NADPH to generate carbohydrates.
6. The thylakoid space and the intermembrane space of a mitochondrion have analogous roles. Students might be encouraged to create a list of the similarities in structure and function of mitochondria and chloroplasts through these related chapters. 22

23. 23 Light energy 6 CO2 6 H2O C6H12O6 6 O2 Photo- synthesis Carbon
Figure 7-UN01
Light
energy
6 CO2
6 H2O
C6H12O6
6 O2
Photo-
synthesis
Carbon
dioxide
Water
Glucose
Oxygen gas
In-text figure, leaf with photosynthesis equation, p. 109 23

24. The Simplified Equation for Photosynthesis
In photosynthesis,
sunlight provides the energy,
electrons are boosted “uphill” and added to carbon dioxide, and
sugar is produced.
© 2013 Pearson Education, Inc.
Student Misconceptions and Concerns
1. Students often do not fully understand how the burning of fossil fuels contributes to global warming. They might wonder, “How does the burning of fossil fuels differ from the burning of ethanol produced from crops?” Students might not realize that the carbon in fossil fuels was removed from the atmosphere hundreds of millions of years ago, while the carbon in crops was removed much more recently, when the crops were grown. The use of ethanol as an alternative is complicated by the typical reliance upon fossil fuels for ethanol production.
2. Some students do not realize that plant cells also have mitochondria. Instead, they assume that the chloroplasts are sufficient for the plant cell’s needs. But nearly 50% of the carbohydrates produced by plant cells are used for cellular respiration (involving mitochondria).
3. Students may not connect the growth in plant mass to the fixation of carbon during the Calvin cycle. It can be difficult for many students to appreciate that molecules in air can contribute significantly to the mass of plants.
4. Students may understand the overall chemical relationships between photosynthesis and cellular respiration, but many struggle to understand the use of carbon dioxide in the Calvin cycle. Photosynthesis is much more than gas exchange.
5. Students who have not read all of Chapter 7 may not realize that glucose is not the direct product of photosynthesis. Although glucose is shown as a product of photosynthesis, a three-carbon sugar is directly produced (G3P). A plant can use G3P to make many types of organic molecules, including glucose. (The authors address the production of G3P under the section “The Calvin Cycle” later in this chapter.)
Teaching Tips
1. When introducing the diverse ways that plants impact our lives, consider challenging your students to come up with a list of products made from plants that they encounter regularly. Perhaps you might only list those encountered in a single day of college life. The list can be surprising and help to build up your “catalog of examples.”
2. The living world contains many examples of adaptations to increase surface area. Some examples are the many folds of the inner mitochondrial membrane, the highly branched surfaces of fish gills and human lungs, and the highly branched system of capillaries in the tissues of our bodies. Consider relating this broad principle seen elsewhere to the extensive folding of the thylakoid membranes.
3. In our world, energy is frequently converted to a usable form in one place and used in another. For example, electricity is generated by power plants, transferred to our homes, and used to run computers, create light, and help us prepare foods. Consider relating this common energy transfer to the two-stage process of photosynthesis.
4. You might wish to discuss the evolution of chloroplasts from photosynthetic prokaryotes if you will not address this subject elsewhere in your course.
5. Figure 7.3 is an important visual organizer that notes the key structures and functions of the two stages of photosynthesis. This figure reminds students where water and sunlight are used in the thylakoid membranes to generate oxygen, ATP, and NADPH. The second step, in the stroma, reveals the use of carbon dioxide, ATP, and NADPH to generate carbohydrates.
6. The thylakoid space and the intermembrane space of a mitochondrion have analogous roles. Students might be encouraged to create a list of the similarities in structure and function of mitochondria and chloroplasts through these related chapters. 24

25. The Simplified Equation for Photosynthesis
During photosynthesis, water is split into
hydrogen and
oxygen.
Hydrogen is transferred along with electrons and added to carbon dioxide to produce sugar.
Oxygen escapes through stomata into the atmosphere.
© 2013 Pearson Education, Inc.
Student Misconceptions and Concerns
1. Students often do not fully understand how the burning of fossil fuels contributes to global warming. They might wonder, “How does the burning of fossil fuels differ from the burning of ethanol produced from crops?” Students might not realize that the carbon in fossil fuels was removed from the atmosphere hundreds of millions of years ago, while the carbon in crops was removed much more recently, when the crops were grown. The use of ethanol as an alternative is complicated by the typical reliance upon fossil fuels for ethanol production.
2. Some students do not realize that plant cells also have mitochondria. Instead, they assume that the chloroplasts are sufficient for the plant cell’s needs. But nearly 50% of the carbohydrates produced by plant cells are used for cellular respiration (involving mitochondria).
3. Students may not connect the growth in plant mass to the fixation of carbon during the Calvin cycle. It can be difficult for many students to appreciate that molecules in air can contribute significantly to the mass of plants.
4. Students may understand the overall chemical relationships between photosynthesis and cellular respiration, but many struggle to understand the use of carbon dioxide in the Calvin cycle. Photosynthesis is much more than gas exchange.
5. Students who have not read all of Chapter 7 may not realize that glucose is not the direct product of photosynthesis. Although glucose is shown as a product of photosynthesis, a three-carbon sugar is directly produced (G3P). A plant can use G3P to make many types of organic molecules, including glucose. (The authors address the production of G3P under the section “The Calvin Cycle” later in this chapter.)
Teaching Tips
1. When introducing the diverse ways that plants impact our lives, consider challenging your students to come up with a list of products made from plants that they encounter regularly. Perhaps you might only list those encountered in a single day of college life. The list can be surprising and help to build up your “catalog of examples.”
2. The living world contains many examples of adaptations to increase surface area. Some examples are the many folds of the inner mitochondrial membrane, the highly branched surfaces of fish gills and human lungs, and the highly branched system of capillaries in the tissues of our bodies. Consider relating this broad principle seen elsewhere to the extensive folding of the thylakoid membranes.
3. In our world, energy is frequently converted to a usable form in one place and used in another. For example, electricity is generated by power plants, transferred to our homes, and used to run computers, create light, and help us prepare foods. Consider relating this common energy transfer to the two-stage process of photosynthesis.
4. You might wish to discuss the evolution of chloroplasts from photosynthetic prokaryotes if you will not address this subject elsewhere in your course.
5. Figure 7.3 is an important visual organizer that notes the key structures and functions of the two stages of photosynthesis. This figure reminds students where water and sunlight are used in the thylakoid membranes to generate oxygen, ATP, and NADPH. The second step, in the stroma, reveals the use of carbon dioxide, ATP, and NADPH to generate carbohydrates.
6. The thylakoid space and the intermembrane space of a mitochondrion have analogous roles. Students might be encouraged to create a list of the similarities in structure and function of mitochondria and chloroplasts through these related chapters. 25

26. A Photosynthesis Road Map
Photosynthesis occurs in two multistep stages:
the light reactions convert solar energy to chemical energy and
the Calvin cycle uses the products of the light reactions to make sugar from carbon dioxide.
© 2013 Pearson Education, Inc.
Student Misconceptions and Concerns
1. Students often do not fully understand how the burning of fossil fuels contributes to global warming. They might wonder, “How does the burning of fossil fuels differ from the burning of ethanol produced from crops?” Students might not realize that the carbon in fossil fuels was removed from the atmosphere hundreds of millions of years ago, while the carbon in crops was removed much more recently, when the crops were grown. The use of ethanol as an alternative is complicated by the typical reliance upon fossil fuels for ethanol production.
2. Some students do not realize that plant cells also have mitochondria. Instead, they assume that the chloroplasts are sufficient for the plant cell’s needs. But nearly 50% of the carbohydrates produced by plant cells are used for cellular respiration (involving mitochondria).
3. Students may not connect the growth in plant mass to the fixation of carbon during the Calvin cycle. It can be difficult for many students to appreciate that molecules in air can contribute significantly to the mass of plants.
4. Students may understand the overall chemical relationships between photosynthesis and cellular respiration, but many struggle to understand the use of carbon dioxide in the Calvin cycle. Photosynthesis is much more than gas exchange.
5. Students who have not read all of Chapter 7 may not realize that glucose is not the direct product of photosynthesis. Although glucose is shown as a product of photosynthesis, a three-carbon sugar is directly produced (G3P). A plant can use G3P to make many types of organic molecules, including glucose. (The authors address the production of G3P under the section “The Calvin Cycle” later in this chapter.)
Teaching Tips
1. When introducing the diverse ways that plants impact our lives, consider challenging your students to come up with a list of products made from plants that they encounter regularly. Perhaps you might only list those encountered in a single day of college life. The list can be surprising and help to build up your “catalog of examples.”
2. The living world contains many examples of adaptations to increase surface area. Some examples are the many folds of the inner mitochondrial membrane, the highly branched surfaces of fish gills and human lungs, and the highly branched system of capillaries in the tissues of our bodies. Consider relating this broad principle seen elsewhere to the extensive folding of the thylakoid membranes.
3. In our world, energy is frequently converted to a usable form in one place and used in another. For example, electricity is generated by power plants, transferred to our homes, and used to run computers, create light, and help us prepare foods. Consider relating this common energy transfer to the two-stage process of photosynthesis.
4. You might wish to discuss the evolution of chloroplasts from photosynthetic prokaryotes if you will not address this subject elsewhere in your course.
5. Figure 7.3 is an important visual organizer that notes the key structures and functions of the two stages of photosynthesis. This figure reminds students where water and sunlight are used in the thylakoid membranes to generate oxygen, ATP, and NADPH. The second step, in the stroma, reveals the use of carbon dioxide, ATP, and NADPH to generate carbohydrates.
6. The thylakoid space and the intermembrane space of a mitochondrion have analogous roles. Students might be encouraged to create a list of the similarities in structure and function of mitochondria and chloroplasts through these related chapters. 26

27. A Photosynthesis Road Map
The initial incorporation of carbon from the atmosphere into organic compounds is called carbon fixation.
This lowers the amount of carbon in the air.
Deforestation reduces the ability of the biosphere to absorb carbon by reducing the amount of photosynthetic plant life.
BioFlix Animation: Photosynthesis
© 2013 Pearson Education, Inc.
Student Misconceptions and Concerns
1. Students often do not fully understand how the burning of fossil fuels contributes to global warming. They might wonder, “How does the burning of fossil fuels differ from the burning of ethanol produced from crops?” Students might not realize that the carbon in fossil fuels was removed from the atmosphere hundreds of millions of years ago, while the carbon in crops was removed much more recently, when the crops were grown. The use of ethanol as an alternative is complicated by the typical reliance upon fossil fuels for ethanol production.
2. Some students do not realize that plant cells also have mitochondria. Instead, they assume that the chloroplasts are sufficient for the plant cell’s needs. But nearly 50% of the carbohydrates produced by plant cells are used for cellular respiration (involving mitochondria).
3. Students may not connect the growth in plant mass to the fixation of carbon during the Calvin cycle. It can be difficult for many students to appreciate that molecules in air can contribute significantly to the mass of plants.
4. Students may understand the overall chemical relationships between photosynthesis and cellular respiration, but many struggle to understand the use of carbon dioxide in the Calvin cycle. Photosynthesis is much more than gas exchange.
5. Students who have not read all of Chapter 7 may not realize that glucose is not the direct product of photosynthesis. Although glucose is shown as a product of photosynthesis, a three-carbon sugar is directly produced (G3P). A plant can use G3P to make many types of organic molecules, including glucose. (The authors address the production of G3P under the section “The Calvin Cycle” later in this chapter.)
Teaching Tips
1. When introducing the diverse ways that plants impact our lives, consider challenging your students to come up with a list of products made from plants that they encounter regularly. Perhaps you might only list those encountered in a single day of college life. The list can be surprising and help to build up your “catalog of examples.”
2. The living world contains many examples of adaptations to increase surface area. Some examples are the many folds of the inner mitochondrial membrane, the highly branched surfaces of fish gills and human lungs, and the highly branched system of capillaries in the tissues of our bodies. Consider relating this broad principle seen elsewhere to the extensive folding of the thylakoid membranes.
3. In our world, energy is frequently converted to a usable form in one place and used in another. For example, electricity is generated by power plants, transferred to our homes, and used to run computers, create light, and help us prepare foods. Consider relating this common energy transfer to the two-stage process of photosynthesis.
4. You might wish to discuss the evolution of chloroplasts from photosynthetic prokaryotes if you will not address this subject elsewhere in your course.
5. Figure 7.3 is an important visual organizer that notes the key structures and functions of the two stages of photosynthesis. This figure reminds students where water and sunlight are used in the thylakoid membranes to generate oxygen, ATP, and NADPH. The second step, in the stroma, reveals the use of carbon dioxide, ATP, and NADPH to generate carbohydrates.
6. The thylakoid space and the intermembrane space of a mitochondrion have analogous roles. Students might be encouraged to create a list of the similarities in structure and function of mitochondria and chloroplasts through these related chapters. 27

28. 28 H2O Chloroplast Light Light reactions ATP – – NADPH O2 Figure 7.3-1
Figure 7.3 A road map for photosynthesis (step 1) 28

29. 29 H2O CO2 Chloroplast Light NADP+ ADP  P Calvin cycle Light
Figure 7.3-2
H2O
CO2
Chloroplast
Light
NADP+
ADP  P
Calvin
cycle
Light
reactions
ATP – –
NADPH O2
Sugar
Figure 7.3 A road map for photosynthesis (step 2) 29

30. THE LIGHT REACTIONS: CONVERTING SOLAR ENERGY TO CHEMICAL ENERGY
Chloroplasts
are chemical factories powered by the sun and
convert sunlight into chemical energy.
© 2013 Pearson Education, Inc.
Student Misconceptions and Concerns
1. The authors note that sunlight is a type of radiation. Many students think of radiation as a result of radioactive decay, a serious threat to health. The diverse types of radiation and the varying energy associated with each, might need to be explained.
2. The authors note that electromagnetic energy travels through space in waves that are like those made by a pebble dropped in a pond. This wave imagery is helpful, but can confuse students when energy is also thought of as discrete packets called photons. The dual nature of light as a wave and particle may need to be discussed further, if students are to do more than just accept the definitions.
3. The light reactions are not solely responsible for all of the products in the general chemical equation of photosynthesis. Point out that oxygen is generated in the light reactions but that glucose results from products of the Calvin cycle.
4. Even at the college level, students struggle to understand why we perceive certain colors. The authors discuss the specific absorption and reflection of certain wavelengths of light, noting which colors are absorbed and which are reflected (and thus available for our eyes to detect). Consider spending time to make sure that your students understand how photosynthetic pigments absorb and reflect certain wavelengths.
Teaching Tips
1. Consider bringing a prism to class and demonstrating the spectrum of visible light. Depending on what you have available, it can be a dramatic reinforcement of this key concept. You might show an image of a rainbow if you are willing to explain how it is produced.
2. Consider bringing a glow stick to class just to help illustrate the authors’ note about the light-generating reactions in glow sticks. Small demonstrations break up lectures and stir attention.
3. The authors discuss a phenomenon that most students have noticed: Dark surfaces heat up faster in the sun than lighter-colored surfaces. This is an opportunity to demonstrate to your students the various depths of scientific explanations and help them appreciate their own educational progress. In elementary school, they might have learned that the sun heats darker surfaces faster than lighter surfaces. In high school, they may have learned about light energy and the fact that dark surfaces absorb more of this energy than lighter surfaces. Now, in college, they are learning that at the atomic level, darker surfaces absorb the energy of more photons, exciting more electrons, which then fall back to a lower state, releasing more heat.
4. The authors develop a mechanical analogy to the energy levels and movement of electrons in the light reaction. Figure 7.12 equates the height of an electron with its energy state. Thus, electrons captured at high levels carry more energy than electrons in lower positions. Although this figure can be very effective, students might need to be carefully led through the analogy to understand precisely what is represented. 30

31. Calvin cycle Light reactions
Figure 7-UN02
CO2
H2O
Light
NADP
ADP + P
Calvin
cycle
Light
reactions
ATP – –
NADPH O2
Sugar
In-text figure, light reactions, p. 110 31

32. The Nature of Sunlight
Sunlight is a type of energy called radiation, or electromagnetic energy.
The distance between the crests of two adjacent waves is called a wavelength.
The full range of radiation is called the electromagnetic spectrum.
© 2013 Pearson Education, Inc.
Student Misconceptions and Concerns
1. The authors note that sunlight is a type of radiation. Many students think of radiation as a result of radioactive decay, a serious threat to health. The diverse types of radiation and the varying energy associated with each, might need to be explained.
2. The authors note that electromagnetic energy travels through space in waves that are like those made by a pebble dropped in a pond. This wave imagery is helpful, but can confuse students when energy is also thought of as discrete packets called photons. The dual nature of light as a wave and particle may need to be discussed further, if students are to do more than just accept the definitions.
3. The light reactions are not solely responsible for all of the products in the general chemical equation of photosynthesis. Point out that oxygen is generated in the light reactions but that glucose results from products of the Calvin cycle.
4. Even at the college level, students struggle to understand why we perceive certain colors. The authors discuss the specific absorption and reflection of certain wavelengths of light, noting which colors are absorbed and which are reflected (and thus available for our eyes to detect). Consider spending time to make sure that your students understand how photosynthetic pigments absorb and reflect certain wavelengths.
Teaching Tips
1. Consider bringing a prism to class and demonstrating the spectrum of visible light. Depending on what you have available, it can be a dramatic reinforcement of this key concept. You might show an image of a rainbow if you are willing to explain how it is produced.
2. Consider bringing a glow stick to class just to help illustrate the authors’ note about the light-generating reactions in glow sticks. Small demonstrations break up lectures and stir attention.
3. The authors discuss a phenomenon that most students have noticed: Dark surfaces heat up faster in the sun than lighter-colored surfaces. This is an opportunity to demonstrate to your students the various depths of scientific explanations and help them appreciate their own educational progress. In elementary school, they might have learned that the sun heats darker surfaces faster than lighter surfaces. In high school, they may have learned about light energy and the fact that dark surfaces absorb more of this energy than lighter surfaces. Now, in college, they are learning that at the atomic level, darker surfaces absorb the energy of more photons, exciting more electrons, which then fall back to a lower state, releasing more heat.
4. The authors develop a mechanical analogy to the energy levels and movement of electrons in the light reaction. Figure 7.12 equates the height of an electron with its energy state. Thus, electrons captured at high levels carry more energy than electrons in lower positions. Although this figure can be very effective, students might need to be carefully led through the analogy to understand precisely what is represented. 32

33. 33 10–5 nm 10–3 nm 1 nm 103 nm 106 nm 1 m 103 m Increasing wavelength
Figure 7.4
Increasing wavelength
10–5 nm
10–3 nm
1 nm
103 nm
106 nm
1 m
103 m
Gamma
rays
Micro-
waves
Radio
waves
X-rays UV
Infrared
Visible light
380
400
500
600
700
750
Wavelength (nm)
Wavelength 
580 nm
Figure 7.4 The electromagnetic spectrum 33

34. 34 Light Reflected light Chloroplast Absorbed light Transmitted
Figure 7.5
Light
Reflected
light
Chloroplast
Absorbed
light
Transmitted
light (detected
by your eye)
Figure 7.5 Why are leaves green? 34

35. 35 Light Reflected light Chloroplast Absorbed light Transmitted
Figure 7.5a
Light
Reflected
light
Chloroplast
Absorbed
light
Transmitted
light (detected
by your eye)
Figure 7.5 Why are leaves green? (part 1) 35

36. Figure 7.5b
Figure 7.5 Why are leaves green? (part 2) 36

37. The Process of Science: What Colors of Light Drive Photosynthesis?
Observation: In 1883, German biologist Theodor Engelmann saw that certain bacteria tend to cluster in areas with higher oxygen concentrations.
Question: Could this information determine which wavelengths of light work best for photosynthesis?
Hypothesis: Oxygen-seeking bacteria will congregate near regions of algae performing the most photosynthesis.
© 2013 Pearson Education, Inc.
Student Misconceptions and Concerns
1. The authors note that sunlight is a type of radiation. Many students think of radiation as a result of radioactive decay, a serious threat to health. The diverse types of radiation and the varying energy associated with each, might need to be explained.
2. The authors note that electromagnetic energy travels through space in waves that are like those made by a pebble dropped in a pond. This wave imagery is helpful, but can confuse students when energy is also thought of as discrete packets called photons. The dual nature of light as a wave and particle may need to be discussed further, if students are to do more than just accept the definitions.
3. The light reactions are not solely responsible for all of the products in the general chemical equation of photosynthesis. Point out that oxygen is generated in the light reactions but that glucose results from products of the Calvin cycle.
4. Even at the college level, students struggle to understand why we perceive certain colors. The authors discuss the specific absorption and reflection of certain wavelengths of light, noting which colors are absorbed and which are reflected (and thus available for our eyes to detect). Consider spending time to make sure that your students understand how photosynthetic pigments absorb and reflect certain wavelengths.
Teaching Tips
1. Consider bringing a prism to class and demonstrating the spectrum of visible light. Depending on what you have available, it can be a dramatic reinforcement of this key concept. You might show an image of a rainbow if you are willing to explain how it is produced.
2. Consider bringing a glow stick to class just to help illustrate the authors’ note about the light-generating reactions in glow sticks. Small demonstrations break up lectures and stir attention.
3. The authors discuss a phenomenon that most students have noticed: Dark surfaces heat up faster in the sun than lighter-colored surfaces. This is an opportunity to demonstrate to your students the various depths of scientific explanations and help them appreciate their own educational progress. In elementary school, they might have learned that the sun heats darker surfaces faster than lighter surfaces. In high school, they may have learned about light energy and the fact that dark surfaces absorb more of this energy than lighter surfaces. Now, in college, they are learning that at the atomic level, darker surfaces absorb the energy of more photons, exciting more electrons, which then fall back to a lower state, releasing more heat.
4. The authors develop a mechanical analogy to the energy levels and movement of electrons in the light reaction. Figure 7.12 equates the height of an electron with its energy state. Thus, electrons captured at high levels carry more energy than electrons in lower positions. Although this figure can be very effective, students might need to be carefully led through the analogy to understand precisely what is represented. 37

38. The Process of Science: What Colors of Light Drive Photosynthesis?
Experiment: Engelmann
laid a string of freshwater algal cells in a drop of water on a microscope slide,
added oxygen-sensitive bacteria to the drop, and
used a prism to create a spectrum of light shining on the slide.
© 2013 Pearson Education, Inc.
Student Misconceptions and Concerns
1. The authors note that sunlight is a type of radiation. Many students think of radiation as a result of radioactive decay, a serious threat to health. The diverse types of radiation and the varying energy associated with each, might need to be explained.
2. The authors note that electromagnetic energy travels through space in waves that are like those made by a pebble dropped in a pond. This wave imagery is helpful, but can confuse students when energy is also thought of as discrete packets called photons. The dual nature of light as a wave and particle may need to be discussed further, if students are to do more than just accept the definitions.
3. The light reactions are not solely responsible for all of the products in the general chemical equation of photosynthesis. Point out that oxygen is generated in the light reactions but that glucose results from products of the Calvin cycle.
4. Even at the college level, students struggle to understand why we perceive certain colors. The authors discuss the specific absorption and reflection of certain wavelengths of light, noting which colors are absorbed and which are reflected (and thus available for our eyes to detect). Consider spending time to make sure that your students understand how photosynthetic pigments absorb and reflect certain wavelengths.
Teaching Tips
1. Consider bringing a prism to class and demonstrating the spectrum of visible light. Depending on what you have available, it can be a dramatic reinforcement of this key concept. You might show an image of a rainbow if you are willing to explain how it is produced.
2. Consider bringing a glow stick to class just to help illustrate the authors’ note about the light-generating reactions in glow sticks. Small demonstrations break up lectures and stir attention.
3. The authors discuss a phenomenon that most students have noticed: Dark surfaces heat up faster in the sun than lighter-colored surfaces. This is an opportunity to demonstrate to your students the various depths of scientific explanations and help them appreciate their own educational progress. In elementary school, they might have learned that the sun heats darker surfaces faster than lighter surfaces. In high school, they may have learned about light energy and the fact that dark surfaces absorb more of this energy than lighter surfaces. Now, in college, they are learning that at the atomic level, darker surfaces absorb the energy of more photons, exciting more electrons, which then fall back to a lower state, releasing more heat.
4. The authors develop a mechanical analogy to the energy levels and movement of electrons in the light reaction. Figure 7.12 equates the height of an electron with its energy state. Thus, electrons captured at high levels carry more energy than electrons in lower positions. Although this figure can be very effective, students might need to be carefully led through the analogy to understand precisely what is represented. 38

39. Animation: Light and Pigments
The Process of Science: What Colors of Light Drive Photosynthesis?
Results: Bacteria
mostly congregated around algae exposed to red-orange and blue-violet light and
rarely moved to areas of green light.
Conclusion: Chloroplasts absorb light mainly in the blue-violet and red-orange part of the spectrum.
Animation: Light and Pigments
© 2013 Pearson Education, Inc.
Student Misconceptions and Concerns
1. The authors note that sunlight is a type of radiation. Many students think of radiation as a result of radioactive decay, a serious threat to health. The diverse types of radiation and the varying energy associated with each, might need to be explained.
2. The authors note that electromagnetic energy travels through space in waves that are like those made by a pebble dropped in a pond. This wave imagery is helpful, but can confuse students when energy is also thought of as discrete packets called photons. The dual nature of light as a wave and particle may need to be discussed further, if students are to do more than just accept the definitions.
3. The light reactions are not solely responsible for all of the products in the general chemical equation of photosynthesis. Point out that oxygen is generated in the light reactions but that glucose results from products of the Calvin cycle.
4. Even at the college level, students struggle to understand why we perceive certain colors. The authors discuss the specific absorption and reflection of certain wavelengths of light, noting which colors are absorbed and which are reflected (and thus available for our eyes to detect). Consider spending time to make sure that your students understand how photosynthetic pigments absorb and reflect certain wavelengths.
Teaching Tips
1. Consider bringing a prism to class and demonstrating the spectrum of visible light. Depending on what you have available, it can be a dramatic reinforcement of this key concept. You might show an image of a rainbow if you are willing to explain how it is produced.
2. Consider bringing a glow stick to class just to help illustrate the authors’ note about the light-generating reactions in glow sticks. Small demonstrations break up lectures and stir attention.
3. The authors discuss a phenomenon that most students have noticed: Dark surfaces heat up faster in the sun than lighter-colored surfaces. This is an opportunity to demonstrate to your students the various depths of scientific explanations and help them appreciate their own educational progress. In elementary school, they might have learned that the sun heats darker surfaces faster than lighter surfaces. In high school, they may have learned about light energy and the fact that dark surfaces absorb more of this energy than lighter surfaces. Now, in college, they are learning that at the atomic level, darker surfaces absorb the energy of more photons, exciting more electrons, which then fall back to a lower state, releasing more heat.
4. The authors develop a mechanical analogy to the energy levels and movement of electrons in the light reaction. Figure 7.12 equates the height of an electron with its energy state. Thus, electrons captured at high levels carry more energy than electrons in lower positions. Although this figure can be very effective, students might need to be carefully led through the analogy to understand precisely what is represented. 39

40. 40 Light Prism Microscope slide Bacteria Bacteria Number of bacteria
Figure 7.6
Light
Prism
Microscope slide
Bacteria
Bacteria
Number of bacteria
Algal cells
400
500
600
700
Wavelength of light (nm)
Figure 7.6 Investigating how light wavelength affects photosynthesis 40

41. Chloroplast Pigments Chloroplasts contain several pigments:
Chlorophyll a
absorbs mainly blue-violet and red light and
participates directly in the light reactions.
Chlorophyll b
absorbs mainly blue and orange light and
participates indirectly in the light reactions.
© 2013 Pearson Education, Inc.
Student Misconceptions and Concerns
1. The authors note that sunlight is a type of radiation. Many students think of radiation as a result of radioactive decay, a serious threat to health. The diverse types of radiation and the varying energy associated with each, might need to be explained.
2. The authors note that electromagnetic energy travels through space in waves that are like those made by a pebble dropped in a pond. This wave imagery is helpful, but can confuse students when energy is also thought of as discrete packets called photons. The dual nature of light as a wave and particle may need to be discussed further, if students are to do more than just accept the definitions.
3. The light reactions are not solely responsible for all of the products in the general chemical equation of photosynthesis. Point out that oxygen is generated in the light reactions but that glucose results from products of the Calvin cycle.
4. Even at the college level, students struggle to understand why we perceive certain colors. The authors discuss the specific absorption and reflection of certain wavelengths of light, noting which colors are absorbed and which are reflected (and thus available for our eyes to detect). Consider spending time to make sure that your students understand how photosynthetic pigments absorb and reflect certain wavelengths.
Teaching Tips
1. Consider bringing a prism to class and demonstrating the spectrum of visible light. Depending on what you have available, it can be a dramatic reinforcement of this key concept. You might show an image of a rainbow if you are willing to explain how it is produced.
2. Consider bringing a glow stick to class just to help illustrate the authors’ note about the light-generating reactions in glow sticks. Small demonstrations break up lectures and stir attention.
3. The authors discuss a phenomenon that most students have noticed: Dark surfaces heat up faster in the sun than lighter-colored surfaces. This is an opportunity to demonstrate to your students the various depths of scientific explanations and help them appreciate their own educational progress. In elementary school, they might have learned that the sun heats darker surfaces faster than lighter surfaces. In high school, they may have learned about light energy and the fact that dark surfaces absorb more of this energy than lighter surfaces. Now, in college, they are learning that at the atomic level, darker surfaces absorb the energy of more photons, exciting more electrons, which then fall back to a lower state, releasing more heat.
4. The authors develop a mechanical analogy to the energy levels and movement of electrons in the light reaction. Figure 7.12 equates the height of an electron with its energy state. Thus, electrons captured at high levels carry more energy than electrons in lower positions. Although this figure can be very effective, students might need to be carefully led through the analogy to understand precisely what is represented. 41

42. Chloroplast Pigments Carotenoids
absorb mainly blue-green light,
participate indirectly in the light reactions, and
absorb and dissipate excessive light energy that might damage chlorophyll.
The spectacular colors of fall foliage are due partly to the yellow-orange light reflected from carotenoids.
© 2013 Pearson Education, Inc.
Student Misconceptions and Concerns
1. The authors note that sunlight is a type of radiation. Many students think of radiation as a result of radioactive decay, a serious threat to health. The diverse types of radiation and the varying energy associated with each, might need to be explained.
2. The authors note that electromagnetic energy travels through space in waves that are like those made by a pebble dropped in a pond. This wave imagery is helpful, but can confuse students when energy is also thought of as discrete packets called photons. The dual nature of light as a wave and particle may need to be discussed further, if students are to do more than just accept the definitions.
3. The light reactions are not solely responsible for all of the products in the general chemical equation of photosynthesis. Point out that oxygen is generated in the light reactions but that glucose results from products of the Calvin cycle.
4. Even at the college level, students struggle to understand why we perceive certain colors. The authors discuss the specific absorption and reflection of certain wavelengths of light, noting which colors are absorbed and which are reflected (and thus available for our eyes to detect). Consider spending time to make sure that your students understand how photosynthetic pigments absorb and reflect certain wavelengths.
Teaching Tips
1. Consider bringing a prism to class and demonstrating the spectrum of visible light. Depending on what you have available, it can be a dramatic reinforcement of this key concept. You might show an image of a rainbow if you are willing to explain how it is produced.
2. Consider bringing a glow stick to class just to help illustrate the authors’ note about the light-generating reactions in glow sticks. Small demonstrations break up lectures and stir attention.
3. The authors discuss a phenomenon that most students have noticed: Dark surfaces heat up faster in the sun than lighter-colored surfaces. This is an opportunity to demonstrate to your students the various depths of scientific explanations and help them appreciate their own educational progress. In elementary school, they might have learned that the sun heats darker surfaces faster than lighter surfaces. In high school, they may have learned about light energy and the fact that dark surfaces absorb more of this energy than lighter surfaces. Now, in college, they are learning that at the atomic level, darker surfaces absorb the energy of more photons, exciting more electrons, which then fall back to a lower state, releasing more heat.
4. The authors develop a mechanical analogy to the energy levels and movement of electrons in the light reaction. Figure 7.12 equates the height of an electron with its energy state. Thus, electrons captured at high levels carry more energy than electrons in lower positions. Although this figure can be very effective, students might need to be carefully led through the analogy to understand precisely what is represented. 42

43. Figure 7.7
Figure 7.7 Photosynthetic pigments 43

44. How Photosystems Harvest Light Energy
Light behaves as photons, a fixed quantity of light energy.
Chlorophyll molecules absorb photons.
Electrons in the pigment gain energy.
As the electrons fall back to their ground state, energy is released as heat or light.
© 2013 Pearson Education, Inc.
Student Misconceptions and Concerns
1. The authors note that sunlight is a type of radiation. Many students think of radiation as a result of radioactive decay, a serious threat to health. The diverse types of radiation and the varying energy associated with each, might need to be explained.
2. The authors note that electromagnetic energy travels through space in waves that are like those made by a pebble dropped in a pond. This wave imagery is helpful, but can confuse students when energy is also thought of as discrete packets called photons. The dual nature of light as a wave and particle may need to be discussed further, if students are to do more than just accept the definitions.
3. The light reactions are not solely responsible for all of the products in the general chemical equation of photosynthesis. Point out that oxygen is generated in the light reactions but that glucose results from products of the Calvin cycle.
4. Even at the college level, students struggle to understand why we perceive certain colors. The authors discuss the specific absorption and reflection of certain wavelengths of light, noting which colors are absorbed and which are reflected (and thus available for our eyes to detect). Consider spending time to make sure that your students understand how photosynthetic pigments absorb and reflect certain wavelengths.
Teaching Tips
1. Consider bringing a prism to class and demonstrating the spectrum of visible light. Depending on what you have available, it can be a dramatic reinforcement of this key concept. You might show an image of a rainbow if you are willing to explain how it is produced.
2. Consider bringing a glow stick to class just to help illustrate the authors’ note about the light-generating reactions in glow sticks. Small demonstrations break up lectures and stir attention.
3. The authors discuss a phenomenon that most students have noticed: Dark surfaces heat up faster in the sun than lighter-colored surfaces. This is an opportunity to demonstrate to your students the various depths of scientific explanations and help them appreciate their own educational progress. In elementary school, they might have learned that the sun heats darker surfaces faster than lighter surfaces. In high school, they may have learned about light energy and the fact that dark surfaces absorb more of this energy than lighter surfaces. Now, in college, they are learning that at the atomic level, darker surfaces absorb the energy of more photons, exciting more electrons, which then fall back to a lower state, releasing more heat.
4. The authors develop a mechanical analogy to the energy levels and movement of electrons in the light reaction. Figure 7.12 equates the height of an electron with its energy state. Thus, electrons captured at high levels carry more energy than electrons in lower positions. Although this figure can be very effective, students might need to be carefully led through the analogy to understand precisely what is represented. 44

45. 45 (a) Absorption of a photon (b) Fluorescence of a glow stick
Figure 7.8
Excited state
Absorption of a
photon excites
an electron.
The electron
falls to its
ground state. e–
Heat
Light
Light
(fluorescence)
Photon
Ground
state
Chlorophyll
molecule
(a) Absorption of a photon
(b) Fluorescence of a glow stick
Figure 7.8 Excited electrons in pigments 45

46. (a) Absorption of a photon
Figure 7.8a
Excited state
Absorption of a
photon excites
an electron.
The electron
falls to its
ground state. e–
Heat
Light
Light
(fluorescence)
Photon
Ground
state
Chlorophyll
molecule
(a) Absorption of a photon
Figure 7.8 Excited electrons in pigments (part 1) 46

47. (b) Fluorescence of a glow stick
Figure 7.8b
(b) Fluorescence of a glow stick
Figure 7.8 Excited electrons in pigments (part 2) 47

48. How Photosystems Harvest Light Energy
In the thylakoid membrane, chlorophyll molecules are organized with other molecules into photosystems.
A photosystem is a cluster of a few hundred pigment molecules that function as a light-gathering antenna.
© 2013 Pearson Education, Inc.
Student Misconceptions and Concerns
1. The authors note that sunlight is a type of radiation. Many students think of radiation as a result of radioactive decay, a serious threat to health. The diverse types of radiation and the varying energy associated with each, might need to be explained.
2. The authors note that electromagnetic energy travels through space in waves that are like those made by a pebble dropped in a pond. This wave imagery is helpful, but can confuse students when energy is also thought of as discrete packets called photons. The dual nature of light as a wave and particle may need to be discussed further, if students are to do more than just accept the definitions.
3. The light reactions are not solely responsible for all of the products in the general chemical equation of photosynthesis. Point out that oxygen is generated in the light reactions but that glucose results from products of the Calvin cycle.
4. Even at the college level, students struggle to understand why we perceive certain colors. The authors discuss the specific absorption and reflection of certain wavelengths of light, noting which colors are absorbed and which are reflected (and thus available for our eyes to detect). Consider spending time to make sure that your students understand how photosynthetic pigments absorb and reflect certain wavelengths.
Teaching Tips
1. Consider bringing a prism to class and demonstrating the spectrum of visible light. Depending on what you have available, it can be a dramatic reinforcement of this key concept. You might show an image of a rainbow if you are willing to explain how it is produced.
2. Consider bringing a glow stick to class just to help illustrate the authors’ note about the light-generating reactions in glow sticks. Small demonstrations break up lectures and stir attention.
3. The authors discuss a phenomenon that most students have noticed: Dark surfaces heat up faster in the sun than lighter-colored surfaces. This is an opportunity to demonstrate to your students the various depths of scientific explanations and help them appreciate their own educational progress. In elementary school, they might have learned that the sun heats darker surfaces faster than lighter surfaces. In high school, they may have learned about light energy and the fact that dark surfaces absorb more of this energy than lighter surfaces. Now, in college, they are learning that at the atomic level, darker surfaces absorb the energy of more photons, exciting more electrons, which then fall back to a lower state, releasing more heat.
4. The authors develop a mechanical analogy to the energy levels and movement of electrons in the light reaction. Figure 7.12 equates the height of an electron with its energy state. Thus, electrons captured at high levels carry more energy than electrons in lower positions. Although this figure can be very effective, students might need to be carefully led through the analogy to understand precisely what is represented. 48

49. How Photosystems Harvest Light Energy
The reaction center of the photosystem consists of chlorophyll a molecules that sit next to another molecule called a primary electron acceptor, which traps the light-excited electron from chlorophyll a.
Another team of molecules built into the thylakoid membrane then uses that trapped energy to make
ATP and
NADPH.
© 2013 Pearson Education, Inc.
Student Misconceptions and Concerns
1. The authors note that sunlight is a type of radiation. Many students think of radiation as a result of radioactive decay, a serious threat to health. The diverse types of radiation and the varying energy associated with each, might need to be explained.
2. The authors note that electromagnetic energy travels through space in waves that are like those made by a pebble dropped in a pond. This wave imagery is helpful, but can confuse students when energy is also thought of as discrete packets called photons. The dual nature of light as a wave and particle may need to be discussed further, if students are to do more than just accept the definitions.
3. The light reactions are not solely responsible for all of the products in the general chemical equation of photosynthesis. Point out that oxygen is generated in the light reactions but that glucose results from products of the Calvin cycle.
4. Even at the college level, students struggle to understand why we perceive certain colors. The authors discuss the specific absorption and reflection of certain wavelengths of light, noting which colors are absorbed and which are reflected (and thus available for our eyes to detect). Consider spending time to make sure that your students understand how photosynthetic pigments absorb and reflect certain wavelengths.
Teaching Tips
1. Consider bringing a prism to class and demonstrating the spectrum of visible light. Depending on what you have available, it can be a dramatic reinforcement of this key concept. You might show an image of a rainbow if you are willing to explain how it is produced.
2. Consider bringing a glow stick to class just to help illustrate the authors’ note about the light-generating reactions in glow sticks. Small demonstrations break up lectures and stir attention.
3. The authors discuss a phenomenon that most students have noticed: Dark surfaces heat up faster in the sun than lighter-colored surfaces. This is an opportunity to demonstrate to your students the various depths of scientific explanations and help them appreciate their own educational progress. In elementary school, they might have learned that the sun heats darker surfaces faster than lighter surfaces. In high school, they may have learned about light energy and the fact that dark surfaces absorb more of this energy than lighter surfaces. Now, in college, they are learning that at the atomic level, darker surfaces absorb the energy of more photons, exciting more electrons, which then fall back to a lower state, releasing more heat.
4. The authors develop a mechanical analogy to the energy levels and movement of electrons in the light reaction. Figure 7.12 equates the height of an electron with its energy state. Thus, electrons captured at high levels carry more energy than electrons in lower positions. Although this figure can be very effective, students might need to be carefully led through the analogy to understand precisely what is represented. 49

50. 50 Figure 7.9 Chloroplast Cluster of pigment molecules Photon Primary
electron
acceptor e–
Electron
transfer
Reaction
center
Reaction-
center
chlorophyll a
Pigment
molecules
Thylakoid membrane
Transfer
of energy
Photosystem
Figure 7.9 A photosystem: light-gathering molecules that focus light energy onto a reaction center 50

51. 51 Chloroplast Cluster of pigment molecules Thylakoid membrane
Figure 7.9a
Chloroplast
Cluster of pigment
molecules
Thylakoid membrane
Figure 7.9 A photosystem: light-gathering molecules that focus light energy onto a reaction center (part 1) 51

52. 52 Photon Primary electron acceptor Electron transfer Reaction center
Figure 7.9b
Photon
Primary
electron
acceptor
Electron
transfer e–
Reaction
center
Reaction-
center
chlorophyll a
Pigment
molecules
Transfer
of energy
Photosystem
Figure 7.9 A photosystem: light-gathering molecules that focus light energy onto a reaction center (part 2) 52

53. How the Light Reactions Generate ATP and NADPH
Two types of photosystems cooperate in the light reactions:
the water-splitting photosystem and
the NADPH-producing photosystem.
© 2013 Pearson Education, Inc.
Student Misconceptions and Concerns
1. The authors note that sunlight is a type of radiation. Many students think of radiation as a result of radioactive decay, a serious threat to health. The diverse types of radiation and the varying energy associated with each, might need to be explained.
2. The authors note that electromagnetic energy travels through space in waves that are like those made by a pebble dropped in a pond. This wave imagery is helpful, but can confuse students when energy is also thought of as discrete packets called photons. The dual nature of light as a wave and particle may need to be discussed further, if students are to do more than just accept the definitions.
3. The light reactions are not solely responsible for all of the products in the general chemical equation of photosynthesis. Point out that oxygen is generated in the light reactions but that glucose results from products of the Calvin cycle.
4. Even at the college level, students struggle to understand why we perceive certain colors. The authors discuss the specific absorption and reflection of certain wavelengths of light, noting which colors are absorbed and which are reflected (and thus available for our eyes to detect). Consider spending time to make sure that your students understand how photosynthetic pigments absorb and reflect certain wavelengths.
Teaching Tips
1. Consider bringing a prism to class and demonstrating the spectrum of visible light. Depending on what you have available, it can be a dramatic reinforcement of this key concept. You might show an image of a rainbow if you are willing to explain how it is produced.
2. Consider bringing a glow stick to class just to help illustrate the authors’ note about the light-generating reactions in glow sticks. Small demonstrations break up lectures and stir attention.
3. The authors discuss a phenomenon that most students have noticed: Dark surfaces heat up faster in the sun than lighter-colored surfaces. This is an opportunity to demonstrate to your students the various depths of scientific explanations and help them appreciate their own educational progress. In elementary school, they might have learned that the sun heats darker surfaces faster than lighter surfaces. In high school, they may have learned about light energy and the fact that dark surfaces absorb more of this energy than lighter surfaces. Now, in college, they are learning that at the atomic level, darker surfaces absorb the energy of more photons, exciting more electrons, which then fall back to a lower state, releasing more heat.
4. The authors develop a mechanical analogy to the energy levels and movement of electrons in the light reaction. Figure 7.12 equates the height of an electron with its energy state. Thus, electrons captured at high levels carry more energy than electrons in lower positions. Although this figure can be very effective, students might need to be carefully led through the analogy to understand precisely what is represented. 53

54. 54 1 Water-splitting photosystem Primary electron acceptor Light
Figure
Primary
electron
acceptor 2e –
Light 1
Reaction-
center
chlorophyll
H2O 2e –
Water-splitting
photosystem
2 H  O2
Figure 7.10 The light reactions of photosynthesis (step 1) 54

55. 55 2 1 Water-splitting photosystem Energy to make ATP Primary electron
Figure
Energy
to make
ATP
Primary
electron
acceptor 2 2e –
Electron transport chain
Light 1
Reaction-
center
chlorophyll
H2O 2e –
Water-splitting
photosystem
2 H  O2
Figure 7.10 The light reactions of photosynthesis (step 2) 55

56. 56 3 2 1 NADPH-producing photosystem Water-splitting photosystem
Figure
Primary
electron
acceptor
NADP 2e –
Energy
to make 3
ATP
Primary
electron
acceptor 2e – 2 – –
NADPH 2e –
Light
Electron transport chain
Light
Reaction-
center
chlorophyll 1
Reaction-
center
chlorophyll
NADPH-producing
photosystem
H2O 2e –
Water-splitting
photosystem
2 H  O2
Figure 7.10 The light reactions of photosynthesis (step 3) 56

57. How the Light Reactions Generate ATP and NADPH
The light reactions are located in the thylakoid membrane.
An electron transport chain
connects the two photosystems and
releases energy that the chloroplast uses to make ATP.
© 2013 Pearson Education, Inc.
Student Misconceptions and Concerns
1. The authors note that sunlight is a type of radiation. Many students think of radiation as a result of radioactive decay, a serious threat to health. The diverse types of radiation and the varying energy associated with each, might need to be explained.
2. The authors note that electromagnetic energy travels through space in waves that are like those made by a pebble dropped in a pond. This wave imagery is helpful, but can confuse students when energy is also thought of as discrete packets called photons. The dual nature of light as a wave and particle may need to be discussed further, if students are to do more than just accept the definitions.
3. The light reactions are not solely responsible for all of the products in the general chemical equation of photosynthesis. Point out that oxygen is generated in the light reactions but that glucose results from products of the Calvin cycle.
4. Even at the college level, students struggle to understand why we perceive certain colors. The authors discuss the specific absorption and reflection of certain wavelengths of light, noting which colors are absorbed and which are reflected (and thus available for our eyes to detect). Consider spending time to make sure that your students understand how photosynthetic pigments absorb and reflect certain wavelengths.
Teaching Tips
1. Consider bringing a prism to class and demonstrating the spectrum of visible light. Depending on what you have available, it can be a dramatic reinforcement of this key concept. You might show an image of a rainbow if you are willing to explain how it is produced.
2. Consider bringing a glow stick to class just to help illustrate the authors’ note about the light-generating reactions in glow sticks. Small demonstrations break up lectures and stir attention.
3. The authors discuss a phenomenon that most students have noticed: Dark surfaces heat up faster in the sun than lighter-colored surfaces. This is an opportunity to demonstrate to your students the various depths of scientific explanations and help them appreciate their own educational progress. In elementary school, they might have learned that the sun heats darker surfaces faster than lighter surfaces. In high school, they may have learned about light energy and the fact that dark surfaces absorb more of this energy than lighter surfaces. Now, in college, they are learning that at the atomic level, darker surfaces absorb the energy of more photons, exciting more electrons, which then fall back to a lower state, releasing more heat.
4. The authors develop a mechanical analogy to the energy levels and movement of electrons in the light reaction. Figure 7.12 equates the height of an electron with its energy state. Thus, electrons captured at high levels carry more energy than electrons in lower positions. Although this figure can be very effective, students might need to be carefully led through the analogy to understand precisely what is represented. 57

58. 58 – Figure 7.11 To Calvin cycle Light Light Stroma Thylakoid ATP
NADPH
ATP
ADP  P
NADP H
Stroma
Electron transport
chain
Thylakoid
membrane
Photosystem
Photosystem
ATP
synthase
Inside thylakoid
Electron flow 2e – H H
H2O H H H O2
Thylakoid
membrane
Figure 7.11 How the thylakoid membrane converts light energy to the chemical energy of NADPH and ATP 58

59. 59 Stroma Thylakoid membrane Inside thylakoid Thylakoid membrane H
Figure 7.11a H
Stroma
Electron transport
chain
Thylakoid
membrane
Photosystem
Inside thylakoid 2e –
H2O H O2
Thylakoid
membrane
Figure 7.11 How the thylakoid membrane converts light energy to the chemical energy of NADPH and ATP (part 1) 59

60. 60 To Calvin cycle Light ATP synthase Electron flow H NADPH ATP ADP 
Figure 7.11b
To Calvin cycle
Light – – H
NADPH
ATP
ADP  P
NADP H
Electron transport
chain
Photosystem
ATP
synthase
Electron flow H H H H H
Figure 7.11 How the thylakoid membrane converts light energy to the chemical energy of NADPH and ATP (part 2) 60

61. 61 – – – – – – – – – ATP NADPH Water-splitting photosystem
Figure 7.12 e –
ATP e – e – – –
NADPH e – e – e –
Photon e –
Photon
Water-splitting
photosystem
NADPH-producing
photosystem
Figure 7.12 A hard-hat analogy for the light reactions 61

62. THE CALVIN CYCLE: MAKING SUGAR FROM CARBON DIOXIDE
functions like a sugar factory within a chloroplast and
regenerates the starting material with each turn.
Blast Animation: Photosynthesis: Light-Independent Reactions
© 2013 Pearson Education, Inc.
Student Misconceptions and Concerns
1. Glucose is not the direct product of the Calvin cycle, as might be expected from the general equation for photosynthesis. Instead, G3P, as noted in the text, is the main product. Clarify for students the diverse uses of G3P in the production of many important plant molecules and the advantages of producing a molecule with this flexibility.
Teaching Tips
1. If you can find examples of potted C3, C4, and CAM plants, consider bringing them to class. Referring to living plants in class helps students understand these abstract concepts. Nice photographs can serve as a substitute.
2. Relate the properties of C3 and C4 plants to the regions of the country where each is grown. Students might generally understand that crops have specific requirements, but may not specifically relate these physiological differences to their geographic sites of production or specific evolutionary histories. 62

63. Calvin cycle Light reactions
Figure 7-UN03
CO2
Light
H2O
NADP
ADP + P
Calvin
cycle
Light
reactions
ATP – –
NADPH O2
Sugar
In-text figure, Calvin cycle, p. 115 63

64. 64 1 CO2 (from air) RuBP sugar Three-carbon molecule Calvin cycle P P
Figure
CO2 (from air) 1 P
RuBP sugar
Three-carbon molecule P P
Calvin
cycle
Figure 7.13 The Calvin cycle (step 1) 64

65. 65 1 2 CO2 (from air) RuBP sugar Three-carbon molecule Calvin cycle
Figure
CO2 (from air) 1 P
RuBP sugar
Three-carbon molecule
ATP P P
ADP  P
Calvin
cycle – –
NADPH
NADP
G3P sugar P 2
Figure 7.13 The Calvin cycle (step 2) 65

66. Glucose (and other organic
Figure
CO2 (from air) 1 P
RuBP sugar
Three-carbon molecule
ATP P P
ADP P
Calvin
cycle  – –
NADPH
NADP
G3P sugar
G3P sugar 3 P P 2
G3P sugar
Glucose (and other organic
compounds) P
Figure 7.13 The Calvin cycle (step 3) 66

67. Glucose (and other organic
Figure
CO2 (from air) 1 P
RuBP sugar
Three-carbon molecule 4
ATP P P
ADP P
ADP P
Calvin
cycle   – –
NADPH
ATP
NADP
G3P sugar
G3P sugar 3 P P 2
G3P sugar
Glucose (and other organic
compounds) P
Figure 7.13 The Calvin cycle (step 4) 67

68. Evolution Connection: Solar-Driven Evolution
C3 plants
use CO2 directly from the air and
are very common and widely distributed.
© 2013 Pearson Education, Inc.
Student Misconceptions and Concerns
1. Glucose is not the direct product of the Calvin cycle, as might be expected from the general equation for photosynthesis. Instead, G3P, as noted in the text, is the main product. Clarify for students the diverse uses of G3P in the production of many important plant molecules and the advantages of producing a molecule with this flexibility.
Teaching Tips
1. If you can find examples of potted C3, C4, and CAM plants, consider bringing them to class. Referring to living plants in class helps students understand these abstract concepts. Nice photographs can serve as a substitute.
2. Relate the properties of C3 and C4 plants to the regions of the country where each is grown. Students might generally understand that crops have specific requirements, but may not specifically relate these physiological differences to their geographic sites of production or specific evolutionary histories. 68

69. Evolution Connection: Solar-Driven Evolution
C4 plants
close their stomata to save water during hot and dry weather and
can still carry out photosynthesis.
CAM plants
are adapted to very dry climates and
open their stomata only at night to conserve water.
© 2013 Pearson Education, Inc.
Student Misconceptions and Concerns
1. Glucose is not the direct product of the Calvin cycle, as might be expected from the general equation for photosynthesis. Instead, G3P, as noted in the text, is the main product. Clarify for students the diverse uses of G3P in the production of many important plant molecules and the advantages of producing a molecule with this flexibility.
Teaching Tips
1. If you can find examples of potted C3, C4, and CAM plants, consider bringing them to class. Referring to living plants in class helps students understand these abstract concepts. Nice photographs can serve as a substitute.
2. Relate the properties of C3 and C4 plants to the regions of the country where each is grown. Students might generally understand that crops have specific requirements, but may not specifically relate these physiological differences to their geographic sites of production or specific evolutionary histories. 69

70. 70 C4 Pathway CAM Pathway (example: sugarcane) (example: pineapple)
Figure 7.14
ALTERNATIVE PHOTOSYNTHETIC PATHWAYS
C4 Pathway
(example: sugarcane)
CAM Pathway
(example: pineapple)
Cell
type 1
CO2
CO2
Night
Four-carbon
compound
Four-carbon
compound
Cell
type 2
CO2
CO2
Calvin
cycle
Calvin
cycle
Sugar
Sugar
Day
C4 plant
CAM plant
Figure 7.14 C4 and CAM photosynthesis 70

71. C4 Pathway (example: sugarcane) CAM Pathway (example: pineapple)
Figure 7.14a
C4 Pathway
(example: sugarcane)
CAM Pathway
(example: pineapple)
Cell
type 1
CO2
CO2
Night
Four-carbon
compound
Four-carbon
compound
Cell
type 2
CO2
CO2
Calvin
cycle
Calvin
cycle
Sugar
Sugar
Day
CAM plant
C4 plant
Figure 7.14 C4 and CAM photosynthesis (part 1) 71

72. C4 Pathway (example: sugarcane)
Figure 7.14b
C4 Pathway
(example: sugarcane)
Figure 7.14 C4 and CAM photosynthesis (part 2) 72

73. CAM Pathway (example: pineapple)
Figure 7.14c
CAM Pathway
(example: pineapple)
Figure 7.14 C4 and CAM photosynthesis (part 3) 73

74. 74 Light energy Photosynthesis Carbon dioxide Water Glucose Oxygen gas
Figure 7-UN04
Light energy
6 CO2
6 H2O
C6H12O6
6 O2
Photosynthesis
Carbon
dioxide
Water
Glucose
Oxygen
gas
Summary of Key Concepts: The Simplified Equation for Photosynthesis 74

75. 75 Chloroplast CO2 Light H2O Stack of thylakoids NADP Stroma ADP P
Figure 7-UN05
Chloroplast
CO2
Light
H2O
Stack of
thylakoids
NADP
Stroma
ADP P
Calvin
cycle
Light
reactions
ATP – –
NADPH
Sugar used for
cellular respiration
cellulose
starch
other organic compounds O2
Sugar
Summary of Key Concepts: A Photosynthesis Road Map 75

76. 76 + NADP e – 2e – ADP acceptor ATP e – 2e – acceptor – – 2e – NADPH
Figure 7-UN06
NADP e – 2e –
ADP
acceptor
ATP e – 2e –
acceptor – – 2e –
NADPH
Photon
Electron transport chain
Photon
Chlorophyll
H2O
Chlorophyll
NADPH-producing
photosystem 2e –
Water-splitting
photosystem 2 1
2 H O2 +
Summary of Key Concepts: How Photosystems Harvest Light Energy; How the Light Reactions Generate ATP and NADPH 76

77. 77 CO2 Calvin cycle ADP NADP Glucose and other compounds
Figure 7-UN07
CO2
ATP
ADP P
Calvin
cycle – –
NADPH
NADP
G3P
Glucose and
other compounds
(such as cellulose
and starch) P
Summary of Key Concepts: The Calvin Cycle: Making Sugar from Carbon Dioxide 77